KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q102465: How to Use the _MEMVARMASK Variable

Article: Q102465
Product(s): Microsoft FoxPro
Version(s): WINDOWS:2.5x,2.6,2.6a,3.0
Operating System(s): 
Keyword(s): 
Last Modified: 05-FEB-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
- Microsoft FoxPro for Windows, versions 2.5x, 2.6, 2.6a 
-------------------------------------------------------------------------------

SUMMARY
=======

_MEMVARMASK is a variable used in FoxPro for Windows versions 2.5a and later to
make menus work properly with the GraphWizard and spelling checker.

Because of the underscore in the variable name, many people assume it is a system
memory variable and would be displayed on the screen if the following commands
were issued:

  CLEAR MEMORY
  DISPLAY MEMORY

MORE INFORMATION
================

The following text from the 2.5a README.TXT file illustrates the use of
_MEMVARMASK:

===================
Part 4: _MEMVARMASK
===================

Menus you created in FoxPro 2.5 that included expressions may not
have behaved properly when the spelling checker or GraphWizard were
active.

SKIP FOR expressions typically depend on the value of skip variables,
but the skip variables were not visible to your menus when the
spelling checker or GraphWizard was active in FoxPro 2.5. In the
initialization code of the spelling checker and GraphWizard
applications (SPELLCHK.APP and GENGRAPH.APP respectively), PRIVATE ALL
is intentionally issued. This hides skip variables from user-defined
menus and causes a "Variable not found" error when you make a menu
choice.

To correct this situation, the following code is added to the beginning of
the spelling checker and GraphWizard applications:

  IF TYPE("_memvarmask") = "C" and !EMPTY(_memvarmask)
     PRIVATE ALL EXCEPT &_memvarmask
  ELSE
     PRIVATE ALL
  ENDIF

Suppose a certain menu option should be skipped when the memory variable
named "skipvar" evaluates to true. You should include the following lines
in your menu startup code to take advantage of the _MEMVARMASK variable:

  PUBLIC _memvarmask
  _memvarmask = "skipvar"
  STORE .T. TO skipvar             && Skip initially.

To create a set of skip variables, include the following lines in your
menu startup code:

  PUBLIC _memvarmask
  _memvarmask = "skip*"
  STORE .T. TO skipthis, skipthat  && Skip initially.

When you execute the spelling checker and GraphWizard, they don't hide
variables in SKIP FOR expressions, preventing the "Variable not found"
errors you may have experienced in FoxPro 2.5.

Note that _MEMVARMASK isn't a system memory variable.

REFERENCES
==========

Microsoft FoxPro 2.5a for Windows README.TXT file

Additional query words: VFoxWin FoxWin 2.50a 2.50b

======================================================================
Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbFoxproSearch kbFoxPro260 kbFoxPro260a kbVFP300
Version           : WINDOWS:2.5x,2.6,2.6a,3.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.